The modified servo being calibrated on the left half of the screen, with some graphs of its operation being shown on the right half.

Servo Surgery Teaches Us DIY Encoder Implants

Today, we shall talk about how [Adam Bäckström] took a DS3225 servo and rebuilt it to improve its accuracy, then built a high-precision robot arm with those modified servos to show just how much of an improvement he’s got – up to 36 times better positional accuracy. If this brings a déjà vu feeling, that’s because we’ve covered his servo modifications before, but now, there’s more. In a year’s time since the last video came out, [Adam] has taken it to the next level, showing us how the modification is made, and how we ourselves can do it, in a newly released video embedded below.

After ordering replacement controller PCBs designed by [Adam] (assembled by your PCBA service of choice), you disassemble the servo, carefully setting the gearbox aside for now. Gutting the stock control board is the obvious next step, but from there, you don’t just drop the new PCB in – there’s more to getting a perfect servo than this, you have to add extra sensing, too. First, you have to print a spacer and a cover for the control board, as well as a new base for the motor. You also have to print (or perhaps, laser-cut) two flat encoder disks, one black and one white, the white one being eccentric. It only escalates from here!

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Industrial Sewing Machine: Acquired

Well, it’s done. After weeks of trawling Craigslist, an hour-long phone call with an intelligent stranger about a different machine that wasn’t going suit my needs, and a two-week delay while the seller and I waited out their unintentional COVID exposure, I am the proud new owner of a vintage Consew 206RB-3 industrial sewing machine.

So far, it is exactly what I wanted — at least a few decades old, in decent shape, built by a reputable maker, and it has a clutch motor that I can upgrade to a servo motor if I wish. I even like the color of the head, the table, and the little drawer hiding on the left side. Connie Consew is perfect!

Decidedly Not Portable

The internet was right — these things are heavy. According to the manual, the machine head alone weighs 25.5 kg (56 lbs). The motor probably weighs another 50-60 lbs. There’s a small wooden peg sticking up from the table that has the job of holding the head whenever it is tilted back for maintenance or bobbin changes. I’ll admit I didn’t trust the little peg at first, but it does a fine job of supporting all that weight on a single point of contact about an inch in diameter.

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What You Should Know Before Buying An Industrial Sewing Machine

I’ve been sewing off and on since I was a kid, and I really started to get into it about ten years ago. Even though I technically outgrew my little 3/4 size domestic machine pretty quickly, I kept using it because it always did whatever I asked it to. I even made my first backpack on it before deciding it was time for something bigger. Don’t ask me how I managed to not kill that machine, because I have no idea.

Left: a 3/4 size Janome 11706. Right: a full-size Singer Heavy Duty 4452.

Last year, I got a so-called heavy duty Singer that claims to have 50% more power than a standard domestic machine. This bad boy will make purses and backpacks with ease, I thought. And it does. Well, most of the time.

I found its limits when I tried to make a bag out of thick upholstery material. And honestly, when it comes down to finishing most bags — sewing the thickest and most difficult seams — the machine often lifts up from the table on the end opposite the needle.

What I really need is an industrial sewing machine. Not to replace the Singer at all, but to complement it. I can totally justify this purchase. Let me tell you why.

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Eric Strebel peeks through his Pfaff 463 industrial sewing machine.

Simple Upgrades Make An Old Industrial Sewing Machine New Again

Well, this is a pleasant surprise: it seems that industrial designer [Eric Strebel] recently got a hold of an industrial sewing machine to tackle the softer side of prototyping. What doesn’t surprise us is that he did some upgrades to make it more user-friendly. Check them out in the video embedded below.

So, what’s the difference between a machine like this and what you might have around the house? Domestic sewing machines have a motor about the size of your fist, and it’s inside the machine’s body. Modern domestics can do light-duty work, but they can’t handle making bags and upholstery or sewing a bunch of layers of any material together. Industrial machines have either clutch or servo motors that are easily five times the size of a domestic’s motor, and are built into the table along with the machine.

Pfaff 463 industrial sewing machine with its new brushless DC servo motor.[Eric] found this Pfaff 463 on Craigslist. It was built somewhere around 1950, and it only does one thing — a single-needle, straight stitch, forward or reverse — but it will do it through damn near anything you want (unlike those computerized hunks of plastic made for home use nowadays). Again, these machines are always built into a table, and they come with a lamp.  While the machine itself may be a workhorse, the light is wimpy, so [Eric] replaced it with a goose-neck LED light that has a magnet for sticking it anywhere light is required around the machine.

No matter the size, electric sewing machines are driven with a foot pedal. On a domestic, the pedal is loose and you just put it on the floor wherever you want, but industrial foot pedals are built into the table frame. [Eric] drilled a bunch of new holes in the side of the pedal so he can move the connecting rod closer to the pivot point. This gives him better control with less footwork.

The biggest, baddest upgrade [Eric] did was to the motor. Although there was nothing wrong with the original  clutch motor, it makes the machine go very fast so that garment workers can fulfill their quotas. Because of this, it’s difficult to control. He upgraded to a brushless DC servo motor for greater precision and easier prototyping. He got really lucky, too, because it mounted directly into the old holes.

We agree wholeheartedly with [Eric]’s sentiment about old sewing machines, or any old machine for that matter. They tend to be overbuilt because planned obsolescence wasn’t a thing yet. If you can’t afford or find an industrial, an old Singer or something similar will likely serve your purpose, as long as you use the right needle.

If you already have an old domestic machine sitting around, you might be able to breathe new life into it with a 3D printer.

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Automate Your Xbox

First the robots took our jobs, then they came for our video games. This dystopian future is brought to you by [Little French Kev] who designed this adorable 3D-printed robot arm to interface with an Xbox One controller joystick. He shows it off in the video after the break, controlling a ball-balancing physics demonstration written in Unity.

Hats off to him on the quality of the design. There are two parts that nestle the knob of the thumbstick from either side. He mates those pieces with each other using screws, firmly hugging the stick. Bearings are used at the joints for smooth action of the two servo motors that control the arm. The base of the robotic appendage is zip-tied to the controller itself.

The build targets experimentation with machine learning. Since the computer can control the arm via an Arduino, and the computer has access to metrics of what’s happening in the virtual environment, it’s a perfect for training a neural network. Are you thinking what we’re thinking? This is the beginning of hardware speed-running your favorite video games like [SethBling] did for Super Mario World half a decade ago. It will be more impressive since this would be done by automating the mechanical bit of the controller rather than operating purely in the software realm. You’ll just need to do your own hack to implement button control.

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Ultrasonic Sensor Helps You Enforce Social Distancing

If you’re going outside (only for essential grocery runs, we hope) and you’re having trouble measuring the whole six feet apart from other people deal by eye, then [Guido Bonelli] has a solution for you. With a standard old HC-SR04 ultrasonic sensor, an audio module and a servo to drive a custom gauge needle he’s made a device which can warn people around you if they’re too close for comfort.

As simple as this project may sound like for anyone who has a bunch of these little Arduino-compatible modules lying around and has probably made something similar to this in their spare time, there’s one key component that gives it an extra bit of polish. [Guido] found out how intermittent the reliability of the ultrasonic sensor was and came up with a clever way to smooth out its output in order to get more accurate readings from it, using a bubble sort algorithm with a twist. Thirteen data points are collected from the sensor, then they are sorted in order to find a temporal middle point, and the three data points at the center of that sort get averaged into the final output. Maybe not necessarily something with scientific accuracy, but exactly the kind of workaround we expect around these parts!

Projects like these to help us enforce measures to slow the spread of the virus are probably a good bet to keep ourselves busy tinkering in our labs, like these sunglasses which help you remember not to touch your face. Make sure to check out this one in action after the break!

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AvoRipe Takes A Firm Grip On The Ultimate First World Food Problem

You don’t have to be an extinct mammal or a Millennial to enjoy the smooth, buttery taste of an avocado. Being psychic on the other hand is definitely an advantage to catch that small, perfect window between raw and rotten of this divaesque fruit. But don’t worry, as modern problems require modern solutions, [Eden Bar-Tov] and [Elad Goldberg] built the AvoRipe, a device to notify you when your next avocado has reached that window.

Taking both the firmness and color of an avocado as indicators of its ripeness into account, the team built a dome holding a TCS3200 color sensor as stand for the avocado itself, and 3D printed a servo-controlled gripper with a force sensor attached to it. Closing the gripper’s arms step by step and reading the force sensor’s value will determine the softness the avocado has reached. Using an ESP8266 as centerpiece, the AvoRipe is turned into a full-blown IoT device, reporting the sensor readings to a smartphone app, and collecting the avocado’s data history on an Adafruit.IO dashboard.

There is unfortunately one big drawback: to calibrate the sensors, a set of nicely, ripe avocados are required, turning the device into somewhat of a chicken and egg situation. Nevertheless, it’s a nice showcase of tying together different platforms available for widescale hobbyist projects. Sure, it doesn’t hurt to know how to do each part from scratch on your own, but on the other hand, why not use the shortcuts that are at our disposal to remove some obstacles — which sometimes might include programming itself.

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